Circuit interrupter



April 22, 1941 I P. DUFFING ,GIRCUIT INTERRUPTER Filed Dec.

m5 m N T 1 A wy haw/40027 WITNESSES:

Patented Apr. 22, 1941 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER tion of Pennsylvania Application December 17, 1938, Serial No. 246,410 In Germany January 29, 1938 3 Claims.

The invention relates to circuit interrupters in general, and more particularly to circuit breakers for use in high voltage circuits.

Attempts have been made to actuate high voltage circuit breakers by air pressure actuating means and air pressure conductors therefor. Such arrangements have not proved entirely satisfactory for the reason that the air pressure medium does not possess the required insulating qualities for high voltage applications. Furthermore it is very diflicult to secure simultaneous operation of the individual phases of the breaker due to the compressibility of the air.

It has also been proposed to actuate circuit breakers hydraulically by means of an oil pressure operated piston. However, in such proposals considerable diliiculties have been encountered with reference to the location and connection of the oil pressure conductors. In the case of cir cuit breakers having a movable switching bar that moves upwardly toward the connecting head at the top of the insulating column or housing, the oil pressure conductors must be brought in through the connecting head. Still greater difficulties are encountered when a breaker of this type is combined with a disconnecting switch, and where the connecting head is equipped with liquid and gas separating devices.

An object of the invention is the provision of a circuit breaker of improved construction which is operated by an oil pressure actuating means mounted within the housing of the breaker, and which avoids the difficulties mentioned in the preceding paragraph.

Another object of the invention is the provision of an oil pressure operated. circuit breaker in which the oil pressure piston connected with the switch member is mounted within the lower por tion of the insulating housing for the breaker and is arranged to move downwardly to effect opening of the breaker.

Another object of the invention is the provision of an oil pressure operated circuit breaker in which the oil pressure conductors for the actuating piston are disposed within the supporting insulator of the circuit breaker.

Another object of the invention is the provision of an oil pressure operated circuit breaker as previously described in which the oil pressure actuating piston and its cylinder are mounted within the supporting insulator of the breaker and insulated from the grounded metal base of the supporting insulator by a body of oil.

Another object of the invention is the provision of a circuit breaker as described in the preced- (Cl. 2ll0150) ing paragraph, in which the metal cylinder and actuating piston are disposed concentrically within one of the oil pressure conductors.

Another object of the invention is the provision of a circuit breaker of improved construction that is simple, compact, and inexpensive to manufacture.

The invention will be best understood from the following detailed description of several embodiments thereof when read in conjunction with the accompanying drawing, in which:

Figure 1 is a vertical sectional view, partly in elevation, of a circuit breaker constructed in accordance with the invention; and

Fig. 2 is a vertical sectional view, partly in elevation, of a modified form of the circuit breaker.

Referring to Fig. 1, the housing of the circuit breaker comprises an upper tubular casing 3 of vitreous insulating material, such as porcelain, which is mounted on a hollow porcelain supporting insulator 5. Interposed between the casing 3 and the supporting insulator 5 is a cylindrical metal flange 1 which forms the lower terminal of the breaker. A metal connecting head or cap 9 mounted on the upper end of the casing 3 closes the upper end of the casing 3 and forms the upper terminal of the breaker. The lower end of the supporting insulator 5 is mounted on and closed by a metal base I I which is at ground potential.

A stationary contact means I3 is mounted within the casing 3 adjacent the upper end thereof, and this contact means is electrically connected to the metal connecting head 9. A cooperating movable contact member I5 is disposed centrally within the casing 3 and mounted for vertical movement therein. The contact member I5 is movable upwardly to closed circuit position in engagement with the stationary contact means [3, and downwardly to an open circuit position away from the stationary contact means.

For actuating the movable contact member I5 to open and to closed circuit position, there is provided an oil pressure operating means indicated generally at ll. The oil pressure operating means comprises an actuating cylinder l9 which is mounted within the lower portion of the casing 3, and an oil pressure operated piston El movab1e in the cylinder [9 and connected directly to the lower end of the movable contact member Hi. The upper end of the cylinder [8 is provided with a packed opening through which the movable contact member l5 extends into the cylinder for connection to the piston 2|.

A pair of oil pressure conducting tubes 23 and 25 of insulating material for conducting oil under pressure to the opposite sides of the piston 2| are mounted inside of the supporting insulator 5. The upper ends of the tubes 23 and 25 extend into the casing 3, the upper end of the tube 23 being connected to the upper end of the cylinder l9, and the upper end of the tube 25 being connected to the bottom of the cylinder l9. The lower ends of the oil pressure conducting tubes 23 and 25 extend through packed openings in the metal base H and are adapted to be connected to a suitable oil pressure control pump (not shown) which is operable to supply oil under pressure through the tubes to the opposite ends of the cylinder I9 to cause the piston 2| to eil'ect opening or closing of the circuit breaker.

The piston 2| and the cylinder l9 are preferably formed of metal, and the cylinder I9 is electrically and mechanically connected directly to the terminal 1. A plurality of spring pressed contact segments 22 are mounted on top of the cylinder l9 and are electrically connected to the cylinder by suitable flexible shunt conductors (not shown). The contact segments 22 are biased into pressure engagement with the movable contact member |5 by means of a circular spring and serve to conduct current from the terminal I and metal cylinder l9 electrically connected thereto to the movable contact mernber.

While the cylinder 9 has been described as preferably being formed of conducting m.aterial it is to be understood that it is within the concept of the invention to have the cylinder constructed of insulating material in which instance the contact segments 22 for conducting current from the terminal I to the movable contact member I5 are connected by flexible shunt conductors directly to the terminal 1.

An arc extinguishing device indicated generally at 21 is mounted inside of the casing 3 above the cylinder IQ for extinguishing arcs drawn between the movable contact member l5 and the stationary contact means l3 during interruption of the circuit. The are extinguishing device 21 is preferably of the expansion type and comprises a stack of alternately disposed annular insulating rings 29 and intermediate diskshaped insulating rings 3| which form an expansible arc extinguishing chamber siu'rounding the path of movement of the movable contact member l5. The are extinguishing structure 21 is supported at its lower end on a plurality of springs 33 above the cylinder IS. The springs 33 permit the rings 29 and 3| to separate and release the gas pressure generated by the arc in the arc extinguishing chamber when the gas pressure attains a predetermined value.

The tubular insulating casing 3 is filled with an insulating liquid 34, preferably oil, up to a level slightly above the lower end of the stationary contact means l3. The supporting insulator 5 is also preferably filled with a body of oil to further insulate the conducting parts which are at a high potential from the grounded metal base H, and to prevent any internal fiashover between the live parts and ground.

A modified form of circuit breaker is shown in Fig. 2. In this embodiment of the invention the parts which correspond in function to those of the embodiment shown in Fig. 1 have been designated by the same reference characters to facilitate a comparison of the two structures. Referring to Fig. 2: In distinction from the embodiment of the invention shown in Fig. 1, the piston 2| and the metal actuating cylinder I!) of this modification of the invention are mounted in the upper portion of the supporting insulator 5. By this arrangement a material reduction in the height of the circuit breaker is obtained. The movable contact member l5 extends through a packed opening provided therefor in a terminal member 1 which is interposed between and separates the casing 3 from the supporting insulator 5, and the lower end of the contact member I5 is connected directly to the oil pressure operated piston 2|. A plurality of contact segments 22 are mounted in a holder on top of the terminal member 1 are electrically connected to the terminal member for conducting current from the terminal I to the movable contact member I5.

The are extinguishing device 21 mounted within the shortened upper insulating casing 3 is supported at its lower end on the springs 33 which rest on the dividing terminal member I.

An oil pressure conducting tube 23 of insulating material is mounted inside the supporting insulator 5 for conducting oil under pressure to the upper open end of the metal cylinder |9. The tube 23 has a relative large diameter and concentrically encloses the metal cylinder Hi. The upper end of the tube 23 fits tightly within a depending circular flange 35 of the terminal member and communicates with the open upper end of the cylinder IS. The lower portion of the tube 23 extends out through a flanged opening provided therefor in the metal base A second oil pressure conducting tube 25 of insulating material extends concentrically within the outer tube 23 and is connected at its upper end to the lower end of the cylinder IS. The tubes 23 and 25 are filled with oil and are adapted to be connected to a suitable control pump which is operable to force oil under pressure through the tubes to either side of the piston 2| to eifect opening or closing of the circuit breaker.

Since the metal cylinder l8 which is at high potential is located in the oil within the outer insulating tube 23, this cylinder is effectively electrically insulated both by the tube 23 and by the oil in the tube 23 from the grounded metal base II. To further increase the resistance to any voltage breakdown between the live parts and the grounded metal base H, the supporting insulator 5 is filled with an insulating liquid 37 preferably oil. This insulating liquid effectively prevents any voltage breakdown taking place within the interior of the insulator 5 due to water or moisture condensation on the inner surface of the insulator. The resistance to voltage breakdown over the path indicated by the arrow 39 is made at least as high if not higher than that of the path indicated by the arrow 4| along the outer surface of the supporting insulator 5.

It will thus be seen that the invention provides a high voltage circuit breaker of simple, compact and inexpensive construction which is operated by an oil pressure actuating means mounted within the supporting insulator. The novel arrangement of the parts leaves the has been described in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details thereof may be made without departing from the spirit of the invention. It is desired therefore that the appended claims be given the broadest reasonable interpretation permissible in the light of the prior art.

I claim as my invention:

1. In a circuit interrupter, a housing comprising a casing of insulating material and a hollow supporting insulator on which said casing is mounted, a grounded base for said insulator, a stationary contact mounted in said casing adjacent the upper end thereof, a cooperating vertically movable contact member in said housing movable upwardly into engagement with said stationary contact and downwardly away from said stationary contact toward the interior of said supporting insulator, oil pressure operating means for said movable contact comprising an actuating cylinder disposed inside said supporting insulator, an oil pressure operated piston movable in said cylinder and connected to the lower end of said movable contact member, an oil pressure conductor of insulating material passing through the grounded base of the supporting insulator extending upwardly in said insulator and communicating with the upper end of the cylinder, said oil pressure conductor being of larger diameter than said cylinder and concentrically enclosing said cylinder, at second oil pressure conductor of insulating material extending concentrically within said first mentioned oil pressure conductor and communicating with the lower end of the cylinder.

2. In a circuit interrupter, a housing comprising a casing of insulating material and a hollow supporting ilnsulator on; which said casing is mounted, said insulator having a grounded base, a stationary contact mounted in said casing adjacent the upper end thereof, a cooperating vertically movable contact member in said housing movable upwardly into engagement with said stationary contact and downwardly away from said stationary contact toward the interior of said supporting insulator, oil pressure operating means for said movable contact comprising an actuating cylinder disposed inside said supporting column, an oil pressure operated piston movable in said cylinder and connected to the lower end of said movable contact member, an oil pressure conducting tube of insulating material passing through the base of the supporting insulator and extending upwardly inside said supporting insulator, said oil conducting tube concentrically enclosing surrounding said actuating cylinder and communicating with the upper end of said cylinder, and a second oil pressure conducting tube of insulating material extending within said first mentioned tube and connected to the lower end of said cylinder, said cylinder being located in the body of oil in said first mentioned tube and insulated from ground thereby, and a body of oil in said supporting insulator surrounding said first mentioned tube.

3. In a circuit breaker, a housing comprising an upper casing of insulating material and a hollow supporting insulator on which said casing is mounted, a stationary contact mounted within said casing adjacent the upper end thereof, a cooperating vertically movable contact member in said housing movable upwardly into engagement with said stationary contact and movable downwardly away from said stationary contact toward the interior of said supporting insulator, an expansible arc extinguishing means in said upper casing below the stationary contact, a grounded metal base closing the lower end of said supporting insulator, oil pressure operating means for said movable contact comprising a metal actuating cylinder mounted inside said supporting insulator in the upper portion thereof, an oil pressure operated piston movable in said cylinder and connected to the lower end of said movable contact member, an oil pressure conducting tube of insulating material inside said supporting insulator, concentrically surrounding said cylinder and communicating with the upper end thereof, said tube extending through the metal base of said supporting insulator, a second oil pressure conducting tube of insulating material extending inside said first mentioned tube and connected to the lower end of said cylinder, and a body of oil in said supporting insulator surrounding said first mentioned tube, said cylinder being insulated from said grounded metal base by said first mentioned tube and the oil therein and also by the body of oil in said supporting insulator.

PAUL DUFFING. 

